Compressed air powered guns or “air guns” utilize a compressed air charged to fire a projectile, such as a pellet, steel “bb” or dart. The projectile is loaded into a projectile chamber that is adjacent to or part of the air gun barrel. To fire the air gun, a compressed air charge is directed through a transfer port and into the projectile chamber. The air charge propels the projectile forward through and out of the muzzle end of the barrel toward a target.
Conventional air guns may include a mechanism to create the compressed air charge that is delivered to the projectile chamber for projectile firing. By way of example, some air guns include a piston that is movable in an air cylinder to provide the compressed air charge. Before firing, the piston is held in a cocked position against the force of an energized mechanical spring or gas strut. Upon firing, the piston is released and the mechanical spring or gas strut drives the piston through the air cylinder, compressing and delivering air from the cylinder and to the projectile chamber through the transfer port. After firing, a lever or other type cocking mechanism may be used to move the piston back to the cocked position for subsequent firing.
Other conventional types of air guns may use a compressed air charge that is held in a compressed air tank prior to firing of the air gun. When such air guns are fired (i.e., the trigger is released) fluid communication is opened between the compressed air tank and the projectile chamber to allow the release of compressed air and firing of a projectile. Such tanks may be sized to hold enough compressed air, or other propellant, to enable firing of multiple projectiles before the tank is refilled with compressed air. Some conventional air guns, often referred to as “pre-charged pneumatic” or “PCP” type air guns use compressed air tanks that are refilled by an external pump or a larger compressed air source, such as a SCUBA tank, to provide compressed air. Other conventional air guns may use a replaceable carbon dioxide charged cartridge to provide compressed gas for projectile firing.